I had the MSDS, but they started rusting all over. Very badly on the y-pipe. Marty at MSDS is a great guy and recoated them for free.
I had to take them out and the SHMs were available to me (used, slightly damaged), so I went with them.
Performance difference is hard to tell, but I think the SHMs are better throughout the band though.
AFAIK, no one has any dyno #s between stock, gutted, MSDS, and SHMs.
But JessMan has baseline #s down and will dyno after he's got the jetcoated MSDS on the car next year.
If I had to do it all over again, I would have done MSDS + jetcoat to avoid the headaches associated with the SHMs.
